1. Field of Invention
The present invention relates to liquid crystal display devices and electronic apparatuses. More specifically, the invention relates to a multi-gap-type transflective liquid crystal display device in which the thicknesses of a liquid crystal layer is enhanced or optimized in accordance with transmissive and reflective display areas.
2. Description of Related Art
Related art transflective liquid crystal display devices combining two types of display modes, such as reflective display and transmissive display modes, produce a clear display even in a dark environment while reducing power consumption. These devices achieve this by selecting the reflective mode or the transmissive mode in accordance with the level of brightness of the ambient light.
Such related art transflective liquid crystal display devices include a liquid crystal display device in which a liquid crystal layer is sandwiched between upper and lower substrates, and a reflective film composed of, for example, aluminum and having slits to pass light therethrough is disposed on the inner surface of the lower substrate such that the reflective film serves as a transflective film. In this case, in the reflective mode, external light incident from the upper substrate side contributes to performing display such that the light is passed through the liquid crystal layer, then reflected from the reflective film disposed on the inner surface of the lower substrate, again passed through the liquid crystal layer; and emitted from the upper substrate. In the transmissive mode, light emitted from a backlight and incident from the lower substrate side contributes to performing display such that the light is passed through the slits of the reflective film and the liquid crystal layer and then emitted outside from the upper substrate. Accordingly, in this case, the areas of the reflective film where the slits are formed serve as the transmissive display areas and other areas having no slit of the reflective film serve as the reflective display areas.
In the transflective liquid crystal display device, since the change in polarization state is a function of the product (i.e., retardation Δn·d) of a degree Δn of the anisotropy of refractive index of liquid crystal and the thickness “d” of a liquid crystal layer, highly visible display can be achieved by enhancing or optimizing the retardation. However, since reflective display light passes through the liquid crystal layer twice while transmissive display light passes through the liquid crystal layer only once, it is difficult to enhance or optimize the retardation Δn·d for both the transmissive display light and the reflective display light. When the thickness of the liquid crystal layer is set so as to provide highly visible display in the reflective mode, the display in the transmissive mode is sacrificed. On the other hand, when the thickness of the liquid crystal layer is set so as to provide highly visible display in the transmissive mode, the display in the reflective mode is sacrificed.
To address or solve the above problem, Japanese Unexamined Patent Application Publication No. 11-242226 discloses a liquid crystal display device having a structure in which a liquid crystal layer is thinner in the reflective display area than in the transmissive display area. Such a structure is called a multi-gap type display device and is achieved, for example, by providing a thickness-adjusting layer to adjust the thickness of the liquid crystal layer, having apertures in parts thereof corresponding to the transmissive display areas, below transparent electrodes of the lower substrate and above the reflective film. That is, since the liquid crystal layer is thicker in the transmissive display area than in the reflective display area by the thickness of the thickness-adjusting layer, the retardation Δn·d can be enhanced or optimized for both the transmissive display light and the reflective display light. When the thickness-adjusting layer is used in order to adjust the thickness of the liquid crystal layer, the thickness-adjusting layer is required to have a considerable thickness. To satisfy such a requirement, the thickness-adjusting layer is formed from a photosensitive resin, for example.